The pharmaceutically active agents lopinavir and ritonavir are well known inhibitors of the Human Immunodeficiency Virus (HIV), which is the causative organism of Acquired Immunodeficiency Syndrome (AIDS). Both ritonavir and lopinavir inhibit HIV by inhibiting HIV proteases. Proteases are enzymes that cleave proteins at specific peptide bonds, and many significant biological functions are controlled or mediated by proteases and their inhibitors. By administering pharmaceutically active agents that inhibit HIV proteases, the replication of HIV in humans can be controlled or ceased.
Although much progress has been made toward treating AIDS, none of the current treatments have proven to be totally effective in reversing the disease. In addition, many of the pharmaceutically active agents useful in treating AIDS have a bitter taste that discourages patients from complying with their drug taking regimen. Therefore, improving the taste of liquid compositions containing pharmaceutically active agents, such as lopinavir and ritonavir, is important in the fight against AIDS.
Flavoring agents for liquid pharmaceuticals are well known. For example, U.S. Pat. No. 5,484,801, which issued on Jan. 16, 1996, discloses the use of such flavoring agents as wild cherry flavor, banana flavor, strawberry flavor, sodium saccharin, citric acid, chocolate mint, and other flavor enhancers in pharmaceutical compositions containing ritonavir. However, there remains a need for improved flavoring systems for liquid pharmaceutical compositions containing pharmaceutically active agents, such as ritonavir and/or lopinavir, which are practically insoluble in water and tend to have a bitter taste.